Preparation, Characteristics, and Controlled Release Efficiency of the Novel PCL-PEG/EM Rod Micelles

In order to achieve sustained and controlled release of the hydrophobic cargoes, improve the bioavailability, and reduce the side effects of antibiotics, the model drug erythromycin (EM) was used to prepare polycaprolactone-polyethylene glycol (PCL-PEG)/EM micelles. PCL-PEG, a biocompatible and biodegradable amphiphilic polymer, was used as carrier material of micelles to optimize the formulation and preparation process by orthogonal design. The morphology, stability, drug loading, and encapsulation efficiency and the in vitro release behavior of the micelles were investigated. In addition, activity assays of anti-Staphylococcus aureus were performed. The results indicated that PCL-PEG/EM were rod-like micelles with an average particle size of 220 ± 2.6  nm and a zeta potential of +19 mV. The average drug loading and encapsulation efficiency were approximately 6.5% and 97.0%, respectively. The micelles were stable in the serum within three days. At the effective concentration of the drug, the formulation indicated no apparent toxicity to the cells. The micelles were able to rapidly enter Staphylococcus aureus (S. aureus) and to provide sustained release cargoes that effectively inhibited S. aureus proliferation. The present study provided a new platform for the rational and effective use of hydrophobic antibiotics to treat infections.